The present invention relates to aqueous coating compositions dryable by baking and useful for anodic dip-electrocoating.
Such compositions are based on a binder of a water-soluble and/or water-dispersible addition compound which is at least partially neutralized with basic compounds and esterified, the addition compound comprising 10-35% by weight of one or several .alpha.,.beta.-unsaturated dicarboxylic acids and 65-90% by weight of a butadiene polymer, which is liquid at 20.degree. C., contains at least 50 molar percent butadiene units and has a molecular weight of 400 to 6,000. They also optionally contain minor amounts of an organic solvent and the customary auxiliary agents and additives.
Such coating compositions are basically conventional (British Pat. No. 1,102,652) and are primarily used for electrophoretic coating methods. The coatings produced from these coating compositions, however, are unsatisfactory from the viewpoint of corrosion protection. Subsequent developments had sought improvement by optimizing the polybutadiene component or by employing additional resins. However, the attained effects nowadays no longer satisfy the increased requirements for corrosion protection, particularly in the field of automobile primer coatings.